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NFS: Enable use of the RWF_DONTCACHE flag on the NFS client

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The NFS client needs to defer dropbehind until after any writes to the
folio have been persisted on the server. Since this may be a 2 step
process, use folio_end_writeback_no_dropbehind() to allow release of the
writeback flag, and then call folio_end_dropbehind() once the COMMIT is
done.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
This commit is contained in:
Trond Myklebust
2025-09-06 12:48:16 -04:00
committed by Anna Schumaker
parent 010054a530
commit 902893e390
3 changed files with 9 additions and 5 deletions
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9
fs/nfs/file.c
View File

@@ -363,6 +363,8 @@ static bool nfs_want_read_modify_write(struct file *file, struct folio *folio,
if (pnfs_ld_read_whole_page(file_inode(file)))
return true;
if (folio_test_dropbehind(folio))
return false;
/* Open for reading too? */
if (file->f_mode & FMODE_READ)
return true;
@@ -382,7 +384,6 @@ static int nfs_write_begin(const struct kiocb *iocb,
loff_t pos, unsigned len, struct folio **foliop,
void **fsdata)
{
fgf_t fgp = FGP_WRITEBEGIN;
struct folio *folio;
struct file *file = iocb->ki_filp;
int once_thru = 0;
@@ -394,10 +395,8 @@ static int nfs_write_begin(const struct kiocb *iocb,
file, mapping->host->i_ino, len, (long long) pos);
nfs_truncate_last_folio(mapping, i_size_read(mapping->host), pos);
fgp |= fgf_set_order(len);
start:
folio = __filemap_get_folio(mapping, pos >> PAGE_SHIFT, fgp,
mapping_gfp_mask(mapping));
folio = write_begin_get_folio(iocb, mapping, pos >> PAGE_SHIFT, len);
if (IS_ERR(folio)) {
ret = PTR_ERR(folio);
goto out;
@@ -411,6 +410,7 @@ static int nfs_write_begin(const struct kiocb *iocb,
} else if (!once_thru &&
nfs_want_read_modify_write(file, folio, pos, len)) {
once_thru = 1;
folio_clear_dropbehind(folio);
ret = nfs_read_folio(file, folio);
folio_put(folio);
if (!ret)
@@ -963,5 +963,6 @@ const struct file_operations nfs_file_operations = {
.splice_write = iter_file_splice_write,
.check_flags = nfs_check_flags,
.setlease = simple_nosetlease,
.fop_flags = FOP_DONTCACHE,
};
EXPORT_SYMBOL_GPL(nfs_file_operations);

1
fs/nfs/nfs4file.c
View File

@@ -456,4 +456,5 @@ const struct file_operations nfs4_file_operations = {
#else
.llseek = nfs_file_llseek,
#endif
.fop_flags = FOP_DONTCACHE,
};

4
fs/nfs/write.c
View File

@@ -296,7 +296,7 @@ static void nfs_folio_end_writeback(struct folio *folio)
{
struct nfs_server *nfss = NFS_SERVER(folio->mapping->host);
folio_end_writeback(folio);
folio_end_writeback_no_dropbehind(folio);
if (atomic_long_dec_return(&nfss->writeback) <
NFS_CONGESTION_OFF_THRESH) {
nfss->write_congested = 0;
@@ -748,6 +748,8 @@ static void nfs_inode_remove_request(struct nfs_page *req)
clear_bit(PG_MAPPED, &req->wb_head->wb_flags);
}
spin_unlock(&mapping->i_private_lock);
folio_end_dropbehind(folio);
}
nfs_page_group_unlock(req);